Final answer:
Nashville, Tennessee is the birthplace of country music and is known for its substantial influence in launching many country music careers, while Memphis, Tennessee is credited for its significant impact on rock n' roll.
Step-by-step explanation:
The birthplace of country music, where many careers were started, is Nashville, Tennessee. This city is famously known as 'Music City' and has been a foundational place for the genre, with the Grand Ole Opry serving as a significant platform for country artists. Although Memphis, Tennessee is renowned for its role in the birth and development of rock n' roll, it is Nashville that holds the title for the origination of country music. Memphis was pivotal for music legends like Elvis Presley, who was an expert in blending various musical styles including gospel, blues, bluegrass, and R&B, and recorded for Sun Records. It was in Memphis that Presley released his first record, which creatively combined different regional musical styles.
However, when speaking specifically about country music and its origins, Nashville is the indisputable cradle of the genre, fostering many country music careers on its famous Music Row. The city's rich musical history and establishments like the Grand Ole Opry have made Nashville the epicenter for country music artists to launch and advance their careers.